In the cold rolling of steel slabs to produce sheets or other shapes, a composition is typically used as a lubricant and cooling medium. These compositions are typically relatively unstable emulsions (intentionally) at the acidic pH of use to cause the oil of the emulsion to deposit onto the surfaces of the metals being rolled. However, it may be difficult to remove these oils from the metal surfaces if necessary prior to the next operation.
High speed tandem mill rolling oils are typically designed to form controlled, unstable emulsions with specific particle size distributions and lubricant deposition rates. Most of these products incorporate combinations of ethoxylated cationic emulsifiers in relatively small quantities, normally less than one percent total concentration, which by nature promote higher deposition rates for a given particle size distribution. Nonionics are also used to some extent, but as with the cationics their total concentration is limited by emulsion stability requirements for lubrication. Additionally, these rolling oils are generally buffered to a pH of less than 7 to minimize the undesirable soap formation.
Regardless of the type of emulsifier, the low total concentration in these rolling oil formulations does not significantly contribute to the ease of rolling oil removal in subsequent cleaning operations. In fact, once neutralized in an alkaline cleaning bath, cationic emulsifers can be almost totally inactivated.
The present invention provides a rolling oil composition that includes an alkaline active surfactant without changing the emulsification characteristics, such as particle size distribution or deposition rate, yet the composition provides drastically improved cleaning efficiency and rinsing properties of the deposited rolling oils in subsequent alkaline cleaning cycles.